catalytic converter meltdown!

S

simpleman01

Member
So, I'm trying to install a new RPM exhaust kit on my Sy. The bolts or studs that clamp the exhaust pipe to the back of the converter are broken off in the flange, so I decide to remove the cat and try and drill out the holes. After cussing everyone ever connected to that truck, I got the converter off and woooooooooooooohhhhhhhhh! It was a blessing in disguise. If I hadn't tried to do things the right way, I never would've discovered this:

badcat003.jpg


I've seen the honeycombs kinda collapse before, but it looks like this thing melted. That could've been a frustrating issue to diagnose in the future. My unscientific opinion is too high EGTs from too much boost?!?
 
Don W.

Don W.

Stab it and steer it
Re: catalytic converter meltdown!

No expert here but I'd guess some combination of high EGT's combined with an over rich condition blow-torched the thing.
 
Luke

Luke

Fish sticks SUCK !!!
Re: catalytic converter meltdown!

could that be from race gas? ive heard of it messing up cats but never seen it
 
mrweelr

mrweelr

New member
Re: catalytic converter meltdown!

Wow, lose that and you should see a nice performance boost! How many miles on the truck? This is exactly why I installed an electric cutout - to bypass that sucker when going all-out:

Underside.JPG
 
S

s_blazin

Donating Member
Re: catalytic converter meltdown!

lucky for us we are one of the few remaining states that have cities that do not completely have DEQ so most cars around here do not have CATS, being the case i have never seen a cat melt before, interesting

on a side note

i like the idea of the cutout, but....seeing how exhaust was built in the above pic wouldn't you lose power by the exhaust blowing into a section of pipe that only moves any exhaust gas at all when the cutoput is open? i mean other than when open it's just blowing into that area but iw ould think it would mess up the flow.

same reason people like mandrel bent as opposed to the squish bend style right?

i would think you would lose some decent power, maybe i'm wrong:dunno:
 
S

simpleman01

Member
Re: catalytic converter meltdown!

Yeah, I'm lucky I caught it. Truck does have an afpr, I believe it is set to stock fuel pressures but I have no way of checking. 65k miles on the truck. Previous owner ran high octane fuel but during his ownership reverted the truck from poor running characteristics back to stock w/ tune up, factory chip, etc. The damage could have been done from prior owners or when truck ran poorly...

Either way I've got a new direct-fit replacement Magnaflow cat on the way from Jeg's. NC requires all factory emissions stuff to be in place (visual inspection). Some urban counties have to pass an emissions test (hooked up to computer sniffer for exhaust analysis - this may not be required anymore). We also just converted state wide to a new computer system that tracks everything inspection related. In the past, it was easy to pay Joe High School at the local oil change $20 to give you a sticker. A local shop just got a $10,000 fine for letting some inspection stuff slide so all the local guys are super tight on making sure everything is 100% legal. I've been fighting the inspection system for 17 years and I'd rather just have an almost legal truck. Plus, its better for the environment.

MrWheelr- super clean truck! Exhaust looks great. When I eventually start upgrading (inevitable!) I'll probably do something very similar.
 
mrweelr

mrweelr

New member
Re: catalytic converter meltdown!

First off, there's no way in hell my truck would ever pass a visual inspection - not going to happen. SMOG time sucks major ass with my truck, but I have my ways of getting it done. I still run a cat because I do care about the environment and don't like breathing noxious exhaust fumes. The truck runs very clean at idle and cruise, I just like having a way to open up the downpipe when racing, which isn't very often. I seriously doubt the cutout hurts performance - in fact, it feels like a shot of NOS when I open that thing up. Maybe someone who had dyno'd one of these things could chime in regarding that. In any case, it sounds incredible at WOT with the QTP cutout open.
 
nello

nello

Active member
Re: catalytic converter meltdown!

Eww, that's nasty! Not sure what end of the cat that is, front or back, but it couldn't have been more than 6months/500 miles ago, tops, I sold the old exhaust to another forum member. At that time I checked the outlet of the cat and it was fine. I would've noticed that. Passed cali smog without a hitch last August.

Yes, AFPR was set to stock pressure. I also ran DM pretty much every time I drove the truck and it reported a perfect ratio while driving, boosting. Ran a little rich on deceleration sometimes.
 
FxsX24

FxsX24

94 S10 to be lowered/v8
Re: catalytic converter meltdown!

what brand cutaway is that, and where did you get it
 
TYRODD

TYRODD

My ass. Look at it.
Re: catalytic converter meltdown!

Yup, my Blazer's cat looked the same if not worse. Too rich! Gut that sucker!
 
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